So, you could probably rock this out more by using some samples that were more "tribal" in sound. You do a good job creating the atmosphere with what you did choose, but the drums sound very "studio" rather than "Tribal" to me. The rhythms are quite cool.
The roars sound a little tongue-in-cheek to me, you could probably get them to sound more aggressive by working in some menacing breathing and more subtle effects and then maybe building up to a roar or something. Just a thought. Thanks for sharing this; please check out some of my tracks if you are so inclined :D